In the case where copyright exists on content data such as music data and image data, the right of the copyright holder may be infringed if appropriate measures for copyright protection have not been taken. On the other hand, if top priority is given to the aim of copyright protection and distribution of content data is obstructed, it may be rather disadvantageous to the copyright holder who may collect royalties when a work is duplicated.
Distribution of content data that is a subject of copyright protection is executed mainly through a digital communication network, broadcast waves and so on. When a user uses these data, it is often the case that the data are once recorded in a certain type of storage medium and then reproduced by a reproducing apparatus. At present, a Hard Disk Drive (HDD) is known as a storage device having a large capacity and a control function with high access performance.
The magnetic disk device is mainly equipped in a recording and playback apparatus fixedly. However, portable types with a copyright protection function have come to exist.
As an apparatus for reproducing data, a recording and playback apparatus used at the time of receiving the distribution of such data, or a portable dedicated reproducing apparatus is used. In a recording and playback apparatus to which a portable storage device can be connected, in order to protect the copyright of data recorded in the storage device, it is important to provide security measures for the recording and playback apparatus and the storage device so that the data recorded in the storage device cannot be reproduced over the range of conditions claimed by the copyright holder. When providing security measures for the device, it is necessary to prevent free access to data in the form of plaintext with respect to transmission and reception of data executed in an area that is freely accessible from within and outside of the device, by carrying out an authentication transaction between devices that transmit and receive the data or by performing encryption processing and so on to the data itself. Meanwhile, as authentication transactions and encryption processing become stricter, more processing is required from the issue of a data use request by the user until the data can actually become available. As a result, there can be a situation where the data cannot be smoothly reproduced.
To deal with such problems, Japanese Patent Publication No. 2007-96783 (“Patent Reference 1”) and Japanese Patent Publication No. 2007-96817 (“Patent Reference 2”) present one solution.
These references describe features such that (1) digital data to be used is encrypted and recorded into an area that can be normally accessed in the storage device, (2) a special access area where key data for decrypting the digital data, and key data output conditions from the storage device and reproduction and drawing conditions for a decrypted content (these are collectively referred to as usage rule data) cannot be acquired or falsified in an unauthorized manner is provided in the storage device and the key data and usage rules are recorded there, and (3) a special procedure (protocol) is used to transfer the key data and usage rule data between the recording and playback apparatus and the storage device and to access the key data and usage rule data recorded in the storage device. As for the special procedure, two types of methods are described.
Also, International Patent Publication WO 01/0133358 (“Patent Reference 3”) and International Patent Publication WO 01/043339 (“Patent Reference 4”) propose measures to protect copyrights by encrypting digital data to be used and preventing unauthorized falsification of a key for executing decryption of the digital data and usage rule information of the decrypted digital data.
Japanese Patent Publication No. 2004-302701 (“Patent Reference 5”) discloses a technique related to a storage device in which, in order to improve tamper-resistance at the time of encrypting data to be concealed and inputting and outputting the data between a storage device and a host apparatus, processing of plural encryption inputs and outputs sent from the host apparatus is divided into plural procedures and processed in parallel.
Also, Japanese Patent Publication No. 2004-7533 (“Patent Reference 6”) discloses a technique for reducing load at the time of accessing encrypted content data.
The two types of management and inter-device transfer methods for key data and usage rule data, described in Patent References 1 and 2, are effective in such a case that a server apparatus or a dynamic image recording and playback device situated at a remote location and a storage device having a control unit therein such as Hard Disk Drive are connected to each other and digital content data that needs protection is transferred. Particularly, in the case where the main object is to provide a service of recording and playback digital television contents, if the host apparatus and the storage device are connected in a BT mode (Bidirectional Transfer) and key data and usage rule data are transferred between these devices, the load of transaction that needs to be executed by the storage device with respect to these data can be restrained to a low level and it is extremely effective. The feature will be described specifically. The following three points can be given.                (1) When authentication transaction (Connection Stage) is executed between a host apparatus and a storage device that are connected to each other for the first time, an authentication log (Connection Log) is recorded. In the next and subsequent authentication transaction, authentication (Reconnection Stage) can be completed by simplified transaction using the information recorded in the log.        (2) In the process of transfer of key data and usage rule data, recording of a process proceeding log (Transaction Log) to enable restoration in the case where these data are lost is not executed in the storage device.        (3) In order to prevent unauthorized duplication and restoration of key data and usage rule data, only one entry is provided in the storage device where the Connection Log may be recorded.        
As a conclusion of (3) of the above points, there is a problem that even in the case where a storage device is connected again to a host apparatus to which the storage device has been connected in the past, if the storage device is temporarily connected to another host apparatus and then reconnected to the former host apparatus, authentication cannot be completed in the Reconnection Stage. Embodiments of the present invention may solve such problems.
In the case of reconnecting a storage device to a host to which it has already been connected (authentication transaction is completed), if Reconnection is to be made after the storage device is connected temporarily to another host (authentication transaction is completed), simplified authentication transaction cannot be executed.